John Entick was annoying. His prose was not particularly good and he used it often to criticize the government of the day, sometimes writing blistering attacks in The Monitor. But the solution to this annoyance was relatively simple: On November 11, 1762, four messengers of the King acting on warrant orders of Lord Halifax broke into Entick’s home to seize his private papers. It didn’t matter that boxes and desks were locked; the locks were easily broken so that their confiscation of anything troublesome could be complete.

Entick challenged the lawfulness of the search in the case of Entick v. Carrington. It would prove to be one of the more important cases in English law that helped to shape the Fourth Amendment to the U.S. Constitution, which asserts the right of individuals not to be subjected to unreasonable searches or seizures by the government without the issuance of a warrant that is based upon probable cause and that is reasonably particular in describing what is to be searched or seized.

Entick prevailed in the case, with the court ruling that the warrant issued by Lord Halifax was defective because there had been no demonstration of probable cause that Entick had committed a crime and because the warrant was too broad in allowing such a general confiscation. While the language in the ruling is somewhat archaic, it can be read here.

The Fourth Amendment to the U.S. Constitution is the most important constraint on the ability of the government to engage in fishing expeditions for evidence of wrongdoing. We all recognize the need for the government at times to engage in searches for evidence; it is a necessary part of the process of law enforcement. But it cannot do so capriciously. There is otherwise too great a potential for misuse of police powers by the state.

At times, it seems as though this fundamental principle is forgotten.

There have been reports in the news over the last several months regarding the use of GPS tracking devices by the police. The pattern is generally the same: the police attach such a device to a vehicleand then keep track of everywhere its owner goes. It is astonishing how much can be inferred about a person’s private life just by having access to that information. What is alarming is not so much that the government makes use of this technology in law enforcement, but that these devices are being used without a warrant ever being issued and that this practice is being sanctioned by at least some courts.

The facts considered in United States of America v. Juan Pineda-Moreno are clear: Drug Enforcement Agency officers saw a group of men buy a large amount of fertilizer often used to grow marijuana and so snuck into the driveway of one of them at about 4:00 AM, attached a GPS device to his Jeep, and then monitored his whereabouts with the device. They had no warrant.

The Ninth Circuit found that this did not violate the Fourth Amendment, even though the Jeep was parked in the man’s driveway at the time. A copy of the opinion can be read here. Other jurisdictions have come to a different view, finding instead that these types of actions — attaching tracking devices to vehicles without a warrant so that a person’s movements can be monitored — do violate the Fourth Amendment, and I find myself in greater sympathy with them.

At issue is what the scope of our rights to be free from “unreasonable” searches should be when technological advances enable the police to monitor people in ever more intrusive ways. An important dissent in the Ninth Circuit case spells out some of the ramifications. A copy of that dissent can be read here (the dissent is technically to a request for en banc rehearing and not to the deciding opinion itself). It is not just GPS devices snuck onto our cars in the dead of night that are used to monitor us. Consider the use of cellular telephones, whose location may also be readily determined. At the request of the government, cell-phone providers will obligingly ping a cell phone to determine its location and provide that information to the police. The provider Sprint has disclosed that last year it provided 8 million such location ping results to the police. The number of requests became so great that Sprint developed an automated web site to enable the police to check on the location of cell phones at will. Services such as LoJack or OnStar are also used by the police to identify the location of vehicles. Credit-card suppliers will inform the police where the cards have been used.

Entick v. Carrington warns us of the potential for abuse when governments are given unfettered power to conduct searches. As the U.S. Supreme Court noted more than a hundred years ago, that case “was welcomed and applauded by the lovers of liberty in the colonies … it may be confidently asserted that its propositions were in the minds of those who framed the fourth amendment to the constitution .” Boyd v. United States, 116 U.S. 616 (1886). It is a mistake to trust governments with that kind of unrestricted power. Not because they will necessarily be malicious in using it — although we are too well aware that that does also happen at times — but more broadly because the natural temptation in pursuing even legitimate ends may perniciously encroach on the rights of those who have done nothing wrong.

As technology continues to advance, we need to be vigilantly on guard to resist that encroachment when we give power to those who govern us.